Am I a total massive jerk?

so me and my boyfriend have been dating for three years and I have been having feelings for his best friend. My boyfriend has been being really distant the last month cause he is getting ready for college. He wasn't treating me right so I broke up with him, now I'm dating his best friend. The three of us still hangout like we always did but now my ex boyfriend has been really sad but hasn't said anything to me or my boyfriend (his best friend). I feel horrible but Gavon (my ex) wasn't acting like a boyfriend and me and Conner (current boyfriend) have had feelings for each other since a little while after me and Gavon started dating. by the way Gavon already has another girlfriend! So I just wanted to know am I a total jerk for breaking up with him for his best friend?